发动机排气噪声测量方法的实验研究

由于在普通实验室条件下纯排气噪声的测量受到背景噪声的干扰,难以获得准确的测试数据,本文提出了两种实用有效的发动机纯排气噪声测量方法,设计了一种圆柱形隔声罩,对发动机外特性曲线上的纯排气噪声进行了试验研究。研究结果表明：本实验装置可行;发动机纯排气噪声强度随转速升高而增大,中高频噪声比例也随之加大;发动机纯排气噪声与背景噪声是相干声波,根据相干声波叠加原理计算出的纯排气噪声与实验值较为吻合,验证了两种测量发动机纯排气噪声方法的可行性。     

智能化声学控制的隔声罩

为了满足机械设备在变工况条件下运行的噪声控制需要,在声学理论的基础上推出作吸声处理隔声罩内任一点的声压随气体媒质压强的变化公式,并将隔声罩技术与PLC控制技术相结合,设计出一种可以根据噪声辐射的强弱自动调整隔声量的智能隔声罩。该隔声罩通过改变罩内的真空度,来对其隔声量进行调节,整个过程是由传感器、PLC及伺服电机等组成的控制系统来实现,能同时完成对低频、中频和高频噪声的控制,具有易于自动化,智能化的特点。某钢铁厂煤气压缩机房一年多的使用情况证实此方法的有效性。     

浅埋工程围护结构传热简化模型误差的有限元分析

为近似计算工程的热湿负荷，通常将地下工程拱形结构的断面等周长地简化为矩形断面。本文采取大型通用有限元分析软件ANSYS对原模型和简化模型进行瞬态热分析，分别对等周长的拱形断面或长方形断面采取等单元密度划分，在两个断面上分别形成间距相同的206个节点，通过不同时间点断面上间距相同的18个节点的平均温度及断面瞬时传热量的比较，判断简化模型的精度。模拟结果表明，简化误差很小，而且随着时间的推移和工程埋深的加大，误差逐渐减小。     

两种建筑围护结构的能耗比较和分析

利用气象温度基础数据，编制建筑能耗模拟程序对建筑围护结构进行动态负荷计算和对比分析；通过计算数据，分析不同设计围护结构的传热性能和热稳定性，为具体应用需要提供选择合适的设计和评价依据。     

小型发电机的噪声治理

本文对便携式发电机的噪声源进行了控制处理,约束阻尼层处理和冷却风扇盖硬化处理,可有效减少噪声级达3dB紧固消音器也可减少噪声级,为发电机设计局部包围,局部包围分别减少声压级和声强级为4dB和3．7dB,同时使用上述噪声控制,第四面上噪声可减小8．5dB,其他面上的噪声也有相应的减小。     

解耦技术在精密控温中的应用

目前世界上一些国家建立了不确定度优于1×10-9量级的电阻标准系统。在此系统中,用于量值比对的电阻必须保持稳定,这一方面要求电阻的材料及制造工艺优良,更重要的是在运输过程中保持电阻传递标准的环境温度高度稳定。但是在制作大容量控温箱时,要实现高度的稳定性和均匀性是非常困难的。传统的解决方案是采用多传感器-多加热器分别测出多个控制点处的温度与设定温度的差值,进而分别调节各点的加热电流。但是点之间的互相耦合使这样的控制过程非常的繁琐。本文提出了一种新颖的解耦方案,通过把控制矩阵的正交化消除了多个控制器-多个传感器之间的互相耦合,使整个系统划分为几个可以独立控制的子系统,控制操作很容易实现。并以此设计制作了一台高精度、大内腔的空气控温箱。实测结果表明月稳定性和温度梯度都在2mK以内,满足了电阻量值传递过程中保存电阻的需求。     

Effects of enclosure size on sexual behavior of Japanese quail (Coturnix japonica).

The authors determined whether results of experiments on copulatory and affiliative behavior of pairs of Japanese quail (Coturnix japonica) conducted in a closely confining apparatus would predict behavior in a large enclosure in which female quail could avoid contact with male quail. As found previously in studies of closely confined quail, in a large enclosure containing numerous barriers, both unmated female quail and mated female quail laying unfertilized eggs were more likely to remain near a confined male quail than were mated female quail laying fertilized eggs. Furthermore, the number of copulations that a pair engaged in when closely confined predicted the number of copulations that they engaged in when they were in the large enclosure. Patterns of affiliation and of mating in a confining laboratory apparatus thus predicted behavior in a larger enclosure that provided female quail with opportunity to avoid contact with male quail. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

大型深基坑自立式围护结构的设计和施工

采用双排灌注桩加环压梁形成基坑围护，辅以分段开挖、外围卸土的措施，使深基坑施工有了安全保证。     

Hold Time Calculations for Non-Standard Enclosures

Current methods of calculating hold time for a fire fighting gas assume that the enclosure is of uniform horizontal cross-sectional area and has horizontal upper and lower boundaries (a standard enclosure). The paper shows that the hold time equation for continuous mixing in standard enclosures may also be used for non-standard enclosures, presents exact and simplified equations for descending interfaces in non-standard enclosures, and discusses the accuracy of the simplified equation. Considering the error when the simplified equation is applied to standard enclosures, and that it is always conservative for an enclosure of any shape, it is suggested that it may be used as an approximation for non-standard enclosures. The paper also presents a hold time equation for a descending interface in a standard enclosure with laminar flow in the leaks.